Semiconductor memory devices

ABSTRACT

Semiconductor memory devices are provided. A semiconductor memory device includes a substrate. The semiconductor memory device includes a plurality of memory cell transistors vertically stacked on the substrate. The semiconductor memory device includes a first conductive line connected to a source region of at least one of the plurality of memory cell transistors. The semiconductor memory device includes a second conductive line connected to a plurality of gate electrodes of the plurality of memory cell transistors. Moreover, the semiconductor memory device includes a data storage element connected to a drain region of the at least one of the plurality of memory cell transistors.

CROSS-REFERENCE TO RELATED APPLICATIONS

This U.S. non-provisional patent application claims the benefit of U.S.provisional Patent Application No. 62/565,302, filed on Sep. 29, 2017,and priority under 35 U.S.C § 119 to Korean Patent Application No.10-2017-0155164, filed on Nov. 20, 2017, the entire contents of whichapplications are hereby incorporated by reference herein.

BACKGROUND

The present disclosure relates to semiconductor devices, and inparticular, to highly-integrated three-dimensional semiconductor memorydevices. Higher integration of semiconductor devices may be used toaddress consumer demands for superior performance and inexpensiveprices. In the case of semiconductor devices, since their integrationmay be an important factor in determining product prices, increasedintegration is especially desirable. In the case of two-dimensional orplanar semiconductor devices, since their integration is mainlydetermined by the area occupied by a unit memory cell, integration canbe greatly influenced by the level of a fine pattern forming technology.However, the expensive process equipment used to increase patternfineness sets a practical limitation on increasing integration fortwo-dimensional or planar semiconductor devices. To overcome such alimitation, three-dimensional semiconductor memory devices includingthree-dimensionally arranged memory cells have recently been proposed.

SUMMARY

Some embodiments of present inventive concepts provide a highlyintegrated three-dimensional semiconductor memory device.

According to some embodiments of present inventive concepts, asemiconductor memory device may include a substrate. The semiconductormemory device may include a plurality of memory cell transistorsvertically stacked on the substrate. The semiconductor memory device mayinclude a first conductive line connected to a source region of at leastone of the plurality of memory cell transistors. The semiconductormemory device may include a second conductive line connected to aplurality of gate electrodes of the plurality of memory celltransistors. Moreover, the semiconductor memory device may include adata storage element connected to a drain region of the at least one ofthe plurality of memory cell transistors. The data storage element mayinclude a first electrode that extends horizontally from the drainregion in a first direction parallel to a top surface of the substrate.A first one of the first conductive line or the second conductive linemay extend horizontally in a second direction that intersects the firstdirection. A second one of the first conductive line or the secondconductive line may extend vertically in a third direction that isperpendicular to the top surface of the substrate.

According to some embodiments of present inventive concepts, asemiconductor memory device may include a substrate. The semiconductormemory device may include a plurality of structures that are verticallyspaced apart from each other in a stack on the substrate. One of theplurality of structures may include a semiconductor pattern thatincludes a first impurity region, a channel region, and a secondimpurity region. The one of the plurality of structures may include afirst electrode of a capacitor that is connected to the second impurityregion. Each of the plurality of structures may extend horizontally in afirst direction that is parallel to a top surface of the substrate.

According to some embodiments of present inventive concepts, asemiconductor memory device may include a substrate. The semiconductormemory device may include a vertical stack including a plurality oflayers on the substrate. The semiconductor memory device may include afirst conductive line that is penetrated by the vertical stack and thatextends in a vertical direction perpendicular to a top surface of thesubstrate. Each of the plurality of layers of the vertical stack mayinclude a first extended portion that extends horizontally in a firstdirection parallel to the top surface of the substrate, and a secondextended portion that extends horizontally from the first extendedportion in a second direction parallel to the top surface of thesubstrate and crossing the first direction. The first extended portionmay include a second conductive line. The second extended portion mayinclude a semiconductor pattern and an electrode that is connected tothe semiconductor pattern. The semiconductor pattern may be between thesecond conductive line and the electrode. Moreover, the first conductiveline may be on a top surface and a bottom surface of the semiconductorpattern.

BRIEF DESCRIPTION OF THE DRAWINGS

Example embodiments will be more clearly understood from the followingbrief description taken in conjunction with the accompanying drawings.The accompanying drawings represent non-limiting, example embodiments asdescribed herein.

FIG. 1 is a circuit diagram schematically illustrating a cell array of athree-dimensional semiconductor memory device according to someembodiments of present inventive concepts.

FIG. 2 is a perspective view illustrating a three-dimensionalsemiconductor memory device according to some embodiments of presentinventive concepts.

FIG. 3A is a sectional view illustrating a portion ‘M’ of FIG. 2.

FIG. 3B is a sectional view illustrating a portion ‘N’ of FIG. 2.

FIG. 4 is a sectional view illustrating a portion (e.g., the portion ‘M’of FIG. 2) of a three-dimensional semiconductor memory device accordingto some embodiments of present inventive concepts.

FIG. 5 is a perspective view illustrating a three-dimensionalsemiconductor memory device according to some embodiments of presentinventive concepts.

FIG. 6A is a sectional view illustrating a portion ‘M’ of FIG. 5.

FIG. 6B is a sectional view illustrating a portion ‘N’ of FIG. 5.

FIG. 7 is a perspective view illustrating a three-dimensionalsemiconductor memory device according to some embodiments of presentinventive concepts.

FIG. 8 is a sectional view illustrating a portion ‘M’ of FIG. 7.

FIG. 9 is a perspective view illustrating a three-dimensionalsemiconductor memory device according to some embodiments of presentinventive concepts.

FIG. 10 is a plan view illustrating a three-dimensional semiconductormemory device according to some embodiments of present inventiveconcepts.

FIGS. 11A, 11B, and 11C are sectional views taken along lines A-A′,B-B′, and C-C′, respectively, of FIG. 10.

FIG. 12 is a perspective view illustrating a three-dimensionalsemiconductor memory device according to some embodiments of presentinventive concepts.

FIGS. 13, 15, 17, 19, 21, 23, 25, 27, 29 and 31 are plan viewsillustrating a method of fabricating a three-dimensional semiconductormemory device, according to some embodiments of present inventiveconcepts.

FIGS. 14, 16A, 18A, 20A, 22A, 24A, 26A, 28A, 30A, and 32A are sectionalviews that are respectively taken along lines A-A′ of FIGS. 13, 15, 17,19, 21, 23, 25, 27, 29, and 31.

FIGS. 16B, 18B, 20B, 22B, 24B, 26B, 28B, 30B, and 32B are sectionalviews that are respectively taken along lines B-B′ of FIGS. 15, 17, 19,21, 23, 25, 27, 29, and 31.

FIGS. 20C, 22C, 24C, 26C, 28C, 30C, and 32C are sectional views that arerespectively taken along lines C-C′ of FIGS. 19, 21, 23, 25, 27, 29, and31.

It should be noted that these figures are intended to illustrate thegeneral characteristics of methods, structure, and/or materials utilizedin example embodiments and to supplement the written descriptionprovided below. These drawings are not, however, to scale and may notprecisely reflect the precise structural or performance characteristicsof any given embodiment, and should not be interpreted as limiting therange of values or properties encompassed by example embodiments. Forexample, the relative thicknesses and positioning of molecules, layers,regions, and/or structural elements may be reduced or exaggerated forclarity. The use of similar or identical reference numbers in thevarious drawings is intended to indicate the presence of a similar oridentical element or feature.

DETAILED DESCRIPTION

FIG. 1 is a circuit diagram schematically illustrating a cell array of athree-dimensional semiconductor memory device according to someembodiments of present inventive concepts.

Referring to FIG. 1, a cell array of a three-dimensional semiconductormemory device may include a plurality of sub-cell arrays SCA. Thesub-cell arrays SCA may be arranged in a second direction D2.

Each of the sub-cell arrays SCA may include a plurality of bit lines BL,a plurality of word lines WL, and a plurality of memory cell transistorsMCT. Each of the memory cell transistors MCT may be placed between acorresponding one of the word lines WL and a corresponding one of thebit lines BL.

The bit lines BL may be conductive patterns (e.g., metal lines), whichare spaced apart from, or stacked on, a substrate. The bit lines BL mayextend in a first direction D1. The bit lines BL in each of the sub-cellarrays SCA may be spaced apart from each other in a vertical direction(e.g., a third direction D3).

The word lines WL may be conductive patterns (e.g., metal line)extending from the substrate in the vertical direction (e.g., in thethird direction D3). The word lines WL in each of the sub-cell arraysSCA may be spaced apart from each other in the first direction D1.

A gate electrode/region of the memory cell transistor MCT may beconnected to the word line WL, and a source electrode/region of thememory cell transistor MCT may be connected to the bit line BL. Each ofthe memory cell transistors MCT may include a capacitor (or other datastorage element) DS. For example, a drain electrode/region of the memorycell transistor MCT may be connected to the capacitor DS.

FIG. 2 is a perspective view illustrating a three-dimensionalsemiconductor memory device according to some embodiments of presentinventive concepts. FIG. 3A is a sectional view illustrating a portion‘M’ of FIG. 2. FIG. 3B is a sectional view illustrating a portion ‘N’ ofFIG. 2.

Referring to FIGS. 1, 2, 3A, and 3B, one of the sub-cell arrays SCAdescribed with reference to FIG. 1 may be provided on a substrate 100.The substrate 100 may be a silicon substrate, a germanium substrate, ora silicon-germanium substrate.

In detail, a stack SS including first to third layers L1, L2, and L3 maybe provided on the substrate 100. The first to third layers L1, L2, andL3 of the stack SS may be stacked to be spaced apart from each other ina vertical direction (i.e., in the third direction D3). Accordingly, thestack SS may be referred to herein as a “vertical stack.” Each of thefirst to third layers L1, L2, and L3 may include a plurality ofsemiconductor patterns SP, a plurality of first electrodes EL1, and afirst conductive line CL1.

Each of the semiconductor patterns SP may extend from the firstconductive lines CL1 in the second direction D2 and may have a lineshape, a bar shape, or a pillar shape. As an example, the semiconductorpatterns SP may be formed of or include silicon, germanium, or silicongermanium. Each of the semiconductor patterns SP may include a channelregion CH, a first impurity region SD1, and a second impurity regionSD2.

The channel region CH may be interposed between the first and secondimpurity regions SD1 and SD2. The channel region CH may be used as achannel region of the memory cell transistor MCT described withreference to FIG. 1. The first and second impurity regions SD1 and SD2may be used as the source and drain electrodes/regions of the memorycell transistor MCT described with reference to FIG. 1. The first andsecond impurity regions SD1 and SD2 may be impurity-doped regions whichare formed by injecting impurities into the semiconductor pattern SP.For example, the first and second impurity regions SD1 and SD2 may havean n- or p-type conductivity.

The first electrodes EL1 may be connected to end portions of thesemiconductor patterns SP, respectively. For example, the firstelectrodes EL1 may be connected to the second impurity regions SD2 ofthe semiconductor patterns SP, respectively. As used herein, the term“connected” may refer to a physical connection and/or an electricalconnection. For example, in some embodiments, a first electrode EL1 maydirectly, physically contact a second impurity region SD2 (e.g., a drainelectrode/region). The first electrodes EL1 may extend from thesemiconductor patterns SP in a horizontal (i.e., lateral) direction suchas the second direction D2. Each of the first electrodes EL1 may have aline shape, a bar shape, or a pillar shape.

A first end portion (e.g., a proximal end portion) of each of the firstelectrodes EL1 may be adjacent and connected to the second impurityregion SD2 of the semiconductor pattern SP, and a second end portion(e.g., a distal end portion) of each of the first electrodes EL1 may beadjacent and connected to a supporting layer SUP. The second end portionof the first electrode EL1 may be opposite to the first end portion ofthe first electrode EL1. Accordingly, it may be possible to define animaginary line connecting (e.g., an axis extending through) the firstand second end portions of each of the first electrodes EL1. Theimaginary line may extend parallel to a top surface of the substrate100. The imaginary line may be parallel to the second direction D2. Theimaginary line may be an extension axis of the first electrode EL1.Furthermore, each of the semiconductor patterns SP may have an extensionaxis parallel to the second direction D2. The extension axes of thesemiconductor pattern SP and the first electrode EL1 connected to thesemiconductor pattern SP may be coaxial/concentric to each other.

The supporting layer SUP may be configured to structurally support thefirst electrode EL1 or to inhibit/prevent the first electrode EL1 frombeing deformed or bent. The supporting layer SUP may be connected incommon to a plurality of the first electrodes EL1. The supporting layerSUP may be formed of or include at least one of various insulatingmaterials (e.g., silicon oxide, silicon nitride, or silicon oxynitride).

Each of the first conductive lines CL1 may have a line or bar shapeextending in the first direction D1. The first conductive lines CL1 maybe stacked to be spaced apart from each other in the third direction D3.The first conductive lines CL1 may be formed of or include at least oneof various conductive materials. For example, the conductive materialsmay include one of doped semiconductor materials (e.g., doped silicon,doped germanium, and so forth), conductive metal nitrides (e.g.,titanium nitride, tantalum nitride, and so forth), metals (e.g.,tungsten, titanium, tantalum, and so forth), and/or metal-semiconductorcompounds (tungsten silicide, cobalt silicide, titanium silicide, and soforth). The first conductive lines CL1 may be used as the bit lines BLdescribed with reference to FIG. 1.

The first layer L1 will be described in detail as a representativeexample of the first to third layers L1, L2 and L3. The semiconductorpatterns SP of the first layer L1 may be arranged to be spaced apartfrom each other in the first direction D1. The semiconductor patterns SPof the first layer L1 may be provided at the same level (e.g., a firstlevel). The first conductive line CL1 of the first layer L1 may beconnected to the first impurity regions SD1 of the semiconductorpatterns SP of the first layer L1. In other words, the first conductiveline CL1 of the first layer L1 may be provided to connect the firstimpurity regions SD1 and to extend in the first direction D1. As anexample, the first conductive line CL1 may be located at the firstlevel, at which the semiconductor patterns SP are located.

The first electrodes EL1 of the first layer L1 may extend from thesemiconductor patterns SP of the first layer L1 in a horizontaldirection such as the second direction D2. The first electrodes EL1 ofthe first layer L1 may be arranged to be spaced apart from each other inthe first direction D1. The first electrodes EL1 of the first layer L1may be provided at the same level (e.g., the first level). In someembodiments, a first electrode EL1 of the first layer L1 may have anupper surface or a lower surface that is coplanar with an upper surfaceor a lower surface of the semiconductor pattern SP of the first layerL1. The first electrodes EL1 may be formed of or include at least one ofvarious conductive materials (e.g., doped semiconductor materials,conductive metal nitrides, metals, or metal-semiconductor compounds).The first electrodes EL1 may include substantially the same material asthat of the first conductive line CL1.

Each of the second layer L2 and the third layer L3 may be configured tohave substantially the same features as the first layer L1. However, thefirst conductive line CL1, the semiconductor patterns SP, and the firstelectrodes EL1 of the second layer L2 may be located at a second levelhigher than the first level, and the first conductive line CL1, thesemiconductor patterns SP, and the first electrodes EL1 of the thirdlayer L3 may be located at a third level higher (in the third directionD3) than the second level.

Referring again to FIG. 3A, a dielectric layer DL may be provided on(e.g., to cover) surfaces of the first electrodes EL1 of the stack SS.The dielectric layer DL may have a uniform thickness on the surface ofthe first electrode EL1. For example, the dielectric layer DL may beformed of or include at least one of metal oxides (e.g., hafnium oxide,zirconium oxide, aluminum oxide, lanthanum oxide, tantalum oxide, andtitanium oxide) or perovskite dielectric materials (e.g., SrTiO₃(STO),(Ba,Sr)TiO₃(BST), BaTiO₃, PZT, and PLZT).

A second electrode EL2 may be provided on the dielectric layer DL. Thesecond electrode EL2 may be provided around a perimeter/periphery of(e.g., to surround) the first electrodes EL1. The second electrode EL2may be formed of or include at least one of conductive materials (e.g.,doped semiconductor materials, conductive metal nitrides, metals, ormetal-semiconductor compounds). Each of the first electrodes ELL thedielectric layer DL, and the second electrode EL2 may constitute thecapacitor DS. The capacitor DS may be used as a memory element forstoring data.

Referring again to FIGS. 1, 2, 3A, and 3B, second conductive lines CL2may be provided on the substrate 100 to penetrate the stack SS. Each ofthe second conductive lines CL2 may have a line shape, a bar shape, or apillar shape extending in the third direction D3. The second conductivelines CL2 may be arranged to be spaced apart from each other in thefirst direction D1.

Each of the second conductive lines CL2 may be provided to extend in thevertical direction (i.e., the third direction D3) and to wrap around(e.g., to surround a periphery of) the semiconductor patterns SP, whichare vertically stacked on the substrate 100. The second conductive lineCL2 may be provided on (e.g., to cover) a top surface, a bottom surface,and opposite side surfaces of the semiconductor pattern SP (e.g., seeFIG. 3B). A gate insulating layer GI may be interposed between thesecond conductive line CL2 and the semiconductor pattern SP. Forexample, the memory cell transistor MCT may be a gate-all-around typetransistor.

The gate insulating layer GI may be formed of or include at least one ofhigh-k dielectric materials, silicon oxide, silicon nitride, or siliconoxynitride and may have a single- or multi-layer structure. For example,the high-k dielectric material may include at least one of hafniumoxide, hafnium silicon oxide, lanthanum oxide, zirconium oxide,zirconium silicon oxide, tantalum oxide, titanium oxide, bariumstrontium titanium oxide, barium titanium oxide, strontium titaniumoxide, lithium oxide, aluminum oxide, lead scandium tantalum oxide, orlead zinc niobate.

As an example, a first one of the second conductive lines CL2 may beprovided to surround a periphery of a first one of the semiconductorpatterns SP of the first layer L1, a first one of the semiconductorpatterns SP of the second layer L2, and a first one of the semiconductorpatterns SP of the third layer L3. A second one of the second conductivelines CL2 may be provided to surround a periphery of a second one of thesemiconductor patterns SP of the first layer L1, a second one of thesemiconductor patterns SP of the second layer L2, and a second one ofthe semiconductor patterns SP of the third layer L3.

The second conductive lines CL2 may be formed of or include at least oneof conductive materials (e.g., doped semiconductor materials, conductivemetal nitrides, metals, or metal-semiconductor compounds). The secondconductive lines CL2 may be used as the word lines WL described withreference to FIG. 1.

The first one of the semiconductor patterns SP in the first layer L1 anda first one of the first electrodes EL1 in the first layer L1 mayconstitute a first structure. The first one of the semiconductorpatterns SP in the second layer L2 and a first one of the firstelectrodes EL1 in the second layer L2 may constitute a second structure.The first one of the semiconductor patterns SP in the third layer L3 anda first one of the first electrodes EL1 in the third layer L3 mayconstitute a third structure. The first to third structures may bestacked to be spaced apart from each other in the vertical direction.The first to third structures may overlap each other in the verticaldirection (i.e., the third direction D3). Each of the first to thirdstructures may have a line shape, a bar shape, or a pillar shapeextending in the second direction D2. Each of the second conductivelines CL2 may be provided to surround a periphery of the semiconductorpatterns SP of the first to third structures.

Empty spaces in the stack SS may include (e.g., be filled with) aninsulating material. For example, the insulating material may be formedof or include at least one of silicon oxide, silicon nitride, or siliconoxynitride.

According to some embodiments of present inventive concepts, athree-dimensional semiconductor memory device may include the memorycell transistors MCT, which are three-dimensionally arranged on thesubstrate 100, and the first electrodes EL1, which are respectivelyconnected to the memory cell transistors MCT and extend horizontally toserve as the capacitors DS. Thus, it is possible to increase anintegration density or capacity of a memory device, compared with theconventional memory device including memory cell transistors, which aretwo-dimensionally arranged on a substrate, and first electrodes, whichare respectively connected thereto and are vertically extended to serveas capacitors.

FIG. 4 is a sectional view illustrating a portion (e.g., the portion ‘M’of FIG. 2) of a three-dimensional semiconductor memory device accordingto some embodiments of present inventive concepts. For concisedescription, an element previously described with reference to FIGS. 1,2, 3A, and 3B may be identified by the same reference number withoutrepeating an overlapping description thereof.

Referring to FIGS. 1, 2, 3B, and 4, each of the first electrodes EL1 mayinclude a semiconductor pillar SPI and a conductive layer TML, which isprovided around a perimeter of (e.g., to surround a surface of) thesemiconductor pillar SPI. For example, the conductive layer TML may beprovided to conformally cover the surface of the semiconductor pillarSPI. The dielectric layer DL may be provided on the conductive layerTML.

The semiconductor pillar SPI may be a pillar-shaped pattern extendingfrom the semiconductor pattern SP in a horizontal direction such as thesecond direction D2. The semiconductor pillar SPI and the semiconductorpattern SP may be connected to constitute a single body. Thesemiconductor pillar SPI may be formed of or include the samesemiconductor material as that of the semiconductor pattern SP. Forexample, the semiconductor pillar SPI may include a doped semiconductormaterial. The conductive layer TML may be formed of or include at leastone of conductive metal nitrides, metals, or metal-semiconductorcompounds.

FIG. 5 is a perspective view illustrating a three-dimensionalsemiconductor memory device according to some embodiments of presentinventive concepts. FIG. 6A is a sectional view illustrating a portion‘M’ of FIG. 5. FIG. 6B is a sectional view illustrating a portion ‘N’ ofFIG. 5. For concise description, an element previously described withreference to FIGS. 1, 2, 3A, and 3B may be identified by the samereference number without repeating an overlapping description thereof.

Referring to FIGS. 1, 5, 6A, and 6B, back-gate lines BG may be providedon the substrate 100 to penetrate the stack SS. Each of the back-gatelines BG may have a line shape, a bar shape, or a pillar shape extendingin the third direction D3. The back-gate lines BG may be arranged to bespaced apart from each other in the first direction D1.

Each of the back-gate lines BG and the second conductive line CL2adjacent thereto may be spaced apart from each other in the seconddirection D2. The back-gate line BG and the second conductive line CL2adjacent thereto may be provided to define a perimeter around (e.g., tosurround a periphery of) the semiconductor pattern SP. The back-gateline BG may be provided to face a top surface, a bottom surface, andopposite side surfaces of the semiconductor pattern SP (e.g., see FIG.6B).

A first gate insulating layer GI1 may be interposed between the secondconductive line CL2 and the semiconductor pattern SP, and a second gateinsulating layer GI2 may be interposed between the back-gate line BG andthe semiconductor pattern SP. The second gate insulating layer GI2 maybe formed of or include at least one of high-k dielectric materials,silicon oxide, silicon nitride, or silicon oxynitride and may beprovided to have a single- or multi-layer structure.

In embodiments where the memory cell transistor MCT is an NMOStransistor, holes may be accumulated in a portion of the semiconductorpattern SP, which is used as the channel region thereof. The back-gateline BG may be used to discharge the holes, which are accumulated in thesemiconductor pattern SP, to the first conductive line CL1. By virtue ofthis discharging operation, it may be possible to stabilize electriccharacteristics of the memory cell transistor MCT.

FIG. 7 is a perspective view illustrating a three-dimensionalsemiconductor memory device according to some embodiments of presentinventive concepts. FIG. 8 is a sectional view illustrating a portion‘M’ of FIG. 7. For concise description, an element previously describedwith reference to FIGS. 1, 2, 3A, and 3B may be identified by the samereference number without repeating an overlapping description thereof.

Referring to FIGS. 1, 7, and 8, a first supporting layer SUP1 and asecond supporting layer SUP2 may be provided on the substrate 100. Thefirst and second supporting layers SUP1 and SUP2 may be connected to thefirst electrodes EL1 of the stack SS and may be used to structurallysupport the first electrodes EL1 of the stack SS. The first supportinglayer SUP1 may be connected to the second end portions of the firstelectrodes ELL and the second supporting layer SUP2 may be connected tomiddle portions of the first electrodes EL1 (e.g., between the first andsecond end portions of the first electrodes EL1). Each of the first andsecond supporting layers SUP1 and SUP2 may include at least one ofsilicon oxide, silicon nitride, or silicon oxynitride, independently.

FIG. 9 is a perspective view illustrating a three-dimensionalsemiconductor memory device according to some embodiments of presentinventive concepts. For concise description, an element previouslydescribed with reference to FIGS. 1, 2, 3A, and 3B may be identified bythe same reference number without repeating an overlapping descriptionthereof.

Referring to FIG. 9, each of the first conductive lines CL1 may beprovided to have a line shape, a bar shape, or a pillar shape extendingin the third direction D3. The first conductive line CL1 may extendvertically to connect vertically-stacked ones of the semiconductorpatterns SP to each other. Each of the second conductive lines CL2 maybe provided to have a line shape, a bar shape, or a pillar shapeextending in the first direction D1. Each of the second conductive linesCL2 may extend horizontally to define a perimeter around (e.g., tosurround a periphery of) the semiconductor patterns SP, which arehorizontally arranged in a corresponding one of the layers L1, L2, L3.

In the semiconductor memory device according to the example of FIG. 9,the bit lines BL (i.e., the first conductive lines CL1) may bevertically extended and the word lines WL (i.e., the second conductivelines CL2) may be horizontally extended, unlike the semiconductor memorydevice described with reference to FIGS. 1, 2, 3A, and 3B. In thesemiconductor memory device according to the example of FIG. 9, thesemiconductor pattern SP and the first electrode EL1 may extend from thefirst conductive line CL1 in a horizontal direction (e.g., in the seconddirection D2).

FIG. 10 is a plan view illustrating a three-dimensional semiconductormemory device according to some embodiments of present inventiveconcepts. FIGS. 11A, 11B, and 11C are sectional views taken along linesA-A′, B-B′, and C-C′, respectively, of FIG. 10. FIG. 12 is a perspectiveview illustrating a three-dimensional semiconductor memory deviceaccording to some embodiments of present inventive concepts. For concisedescription, an element previously described with reference to FIGS. 1,2, 3A, and 3B may be identified by the same reference number withoutrepeating an overlapping description thereof.

Referring to FIGS. 10, 11A to 11C, and 12, the stack SS may be providedon the substrate 100. The stack SS may include first to fourth layersL1, L2, L3, and L4, which are sequentially stacked on the substrate 100.Each of the first to fourth layers L1, L2, L3, and L4 may include thefirst conductive line CL1, the semiconductor patterns SP, and the firstelectrodes EL1. Insulating layers IL4 and IL5 may be interposed betweenthe first to fourth layers L1, L2, L3, and L4. The insulating layers IL4and IL5 may be formed of or include at least one of, for example,silicon oxide, silicon nitride, or silicon oxynitride.

Each of the first to fourth layers L1, L2, L3, and L4 of the stack SSmay include a first extended portion EP1 extending in the firstdirection D1 and second extended portions EP2 extending from the firstextended portion EP1 in the second direction D2. The first extendedportion EP1 may include the first conductive line CL1. The secondextended portion EP2 may include the semiconductor pattern SP and thefirst electrode EL1.

The first conductive line CL1 in each of the first to fourth layers L1,L2, L3, and L4 may extend in the first direction D1. The firstconductive lines CL1 may be used as the bit lines BL described withreference to FIG. 1. The semiconductor patterns SP in each of the firstto fourth layers L1, L2, L3, and L4 may be formed of or include asemiconductor material (e.g., silicon, germanium, or silicon germanium).

First trenches TR1 may be formed to penetrate the stack SS. The secondextended portions EP2 of the stack SS may be defined by the firsttrenches TR1. The first trenches TR1 may be defined between eachadjacent pair of the second extended portions EP2 of the stack SS.

Each first trench TR1 may be provided to horizontally separate adjacentones of the semiconductor patterns SP from each other. The first trenchTR1 may also be provided to horizontally separate adjacent ones of thefirst electrodes EL1 from each other. Moreover, FIGS. 11A and 11Billustrate third trenches TR3 that include the second conductive linesCL2 and the insulating layers IL5 formed therein.

Each of the semiconductor patterns SP may include the channel region CH,the first impurity region SD1, and the second impurity region SD2. Thechannel region CH may be interposed between the first and secondimpurity regions SD1 and SD2. The first conductive line CL1 may beconnected to the first impurity regions SD1 of the semiconductorpatterns SP. The first electrode EL1 may be connected to the secondimpurity region SD2 of the semiconductor pattern SP. The first electrodeEL1 may extend from the second impurity region SD2 of the semiconductorpattern SP in the second direction D2.

The second conductive lines CL2 may be provided to penetrate the stackSS and to extend in the vertical direction (i.e., in the third directionD3). Each of the second conductive lines CL2 may extend in the thirddirection D3 to define a perimeter around (e.g., to surround a peripheryof) vertically-stacked ones of the semiconductor patterns SP. The secondconductive lines CL2 may be spaced apart from each other in the firstdirection D1. The gate insulating layer GI may be provided between thesecond conductive lines CL2 and the semiconductor patterns SP.

The second electrode EL2 may be provided on the first electrodes EL1.The second electrode EL2 may be provided to define a perimeter around(e.g., to surround a periphery of) the first electrodes EL1. Thedielectric layer DL may be interposed between the first electrodes EL1and the second electrode EL2. Each of the first electrodes EL1, thedielectric layer DL, and the second electrode EL2 may constitute thecapacitor DS.

Supporting layers SUP may be provided (e.g., as insulating layers IL3)at both sides of the stack SS. The supporting layer SUP may be connectedin common to end portions of the second extended portions EP2 of thestack SS. The supporting layer SUP may be used to structurally supportthe first electrodes EL1 of the stack SS.

FIGS. 13, 15, 17, 19, 21, 23, 25, 27, 29 and 31 are plan viewsillustrating a method of fabricating a three-dimensional semiconductormemory device, according to some embodiments of present inventiveconcepts. FIGS. 14, 16A, 18A, 20A, 22A, 24A, 26A, 28A, 30A, and 32A aresectional views that are respectively taken along lines A-A′ of FIGS.13, 15, 17, 19, 21, 23, 25, 27, 29, and 31. FIGS. 16B, 18B, 20B, 22B,24B, 26B, 28B, 30B, and 32B are sectional views that are respectivelytaken along lines B-B′ of FIGS. 15, 17, 19, 21, 23, 25, 27, 29, and 31.FIGS. 20C, 22C, 24C, 26C, 28C, 30C, and 32C are sectional views that arerespectively taken along lines C-C′ of FIGS. 19, 21, 23, 25, 27, 29, and31.

Referring to FIGS. 13 and 14, the stack SS may be formed on thesubstrate 100. The formation of the stack SS may include sequentiallyforming the first to fourth layers L1, L2, L3, and L4 on the substrate100. Each of the first to fourth layers L1, L2, L3, and L4 may include afirst insulating layer IL1 and a semiconductor layer SL. Thesemiconductor layer SL may be formed of or include a semiconductormaterial (e.g., silicon, germanium, or silicon germanium). The firstinsulating layer IL1 may be formed of or include at least one of siliconoxide, silicon nitride, or silicon oxynitride. For example, the firstinsulating layer IL1 may include a silicon oxide layer.

An additional first insulating layer IL1 may be formed on the stack SS.For example, the additional first insulating layer IL1 may be furtherformed on (e.g., to cover) the uppermost layer of the semiconductorlayers SL of the stack SS.

Referring to FIGS. 15, 16A, and 16B, a first patterning process may beperformed on the substrate 100 to form the first trenches TR1. The stackSS may be patterned to have the first extended portion EP1 and thesecond extended portions EP2. For example, the first patterning processmay include forming a first mask pattern having first openings, etchingthe stack SS using the first mask pattern as an etch mask, and removingthe first mask pattern. The first trenches TR1 may be formed to expose aportion of the top surface of the substrate 100.

The first extended portion EP1 of the stack SS may be formed to extendin the first direction D1. The second extended portions EP2 of the stackSS may be connected to the first extended portion EP1 and may extend inthe second direction D2. The second extended portions EP2 may be spacedapart from each other in the first direction D1.

Referring to FIGS. 17, 18A, and 18B, a second insulating layer IL2 maybe formed in (e.g., to fill) the first trenches TR1. The secondinsulating layer IL2 may be formed of or include an insulating material,which is the same as or different from the first insulating layer IL1.The second insulating layer IL2 may be formed of or include at least oneof silicon oxide, silicon nitride, or silicon oxynitride. For example,the second insulating layer IL2 may include a silicon oxide layer.

Referring to FIGS. 19 and 20A to 20C, a second patterning process may beperformed on the resulting structure provided with the second insulatinglayer IL2 to form second trenches TR2. The second trenches TR2 may beformed to extend in the first direction D1. For example, the secondpatterning process may include forming a second mask pattern with secondopenings, selectively etching the first insulating layers IL1 using thesecond mask pattern as an etch mask, and removing the second maskpattern.

During the second patterning process, the first insulating layers IL1exposed by the second openings may be selectively removed to form thesecond trenches TR2. The semiconductor patterns SP of the stack SS maybe partially exposed through the second trenches TR2, which are formedby partially and selectively removing the first insulating layers IL1.

Referring to FIGS. 21 and 22A to 22C, a third insulating layer IL3 maybe formed in (e.g., to fill) the second trenches TR2. The thirdinsulating layer IL3 may be formed of or include an insulating materialhaving an etch selectivity with respect to the first and secondinsulating layers IL1 and IL2. The third insulating layer IL3 may beformed of or include at least one of silicon oxide, silicon nitride, orsilicon oxynitride. For example, the third insulating layer IL3 mayinclude a silicon nitride layer. Since the third insulating layer IL3 isformed in (e.g., to fill) the second trench TR2, the third insulatinglayer IL3 may be used to structurally support end portions of the secondextended portions EP2 of the stack SS and/or may be used as thesupporting layer SUP.

Referring to FIGS. 23 and 24A to 24C, the first and second insulatinglayers IL1 and IL2 may be selectively removed. The stack SS includingthe semiconductor layers SL and the third insulating layer IL3 mayremain on the substrate 100.

Since the first and second insulating layers IL1 and IL2 are removed,the semiconductor layers SL may be exposed. An impurity doping processmay be performed on the exposed surfaces of the semiconductor layers SLto form doped regions DR in the semiconductor layers SL. In a subsequentthermal treatment process, the doped impurities may be laterallydiffused from the semiconductor layers SL, and in this case, a portionof the doped region DR may be overlapped by the third insulating layerIL3 in the third direction D3.

Referring to FIGS. 25 and 26A to 26C, the first conductive lines CL1 andthe first electrodes EL1 may be formed by replacing the exposed portionsof the semiconductor layers SL with a conductive material. In someembodiments, a silicidation process may be used to replace the exposedportions of the semiconductor layers SL with the conductive material. Inthe silicidation process, the exposed portions of the semiconductorlayers SL may be reacted with a metallic material, thereby forming ametal-semiconductor compound (e.g., tungsten silicide, cobalt silicide,titanium silicide, and so forth). In some embodiments, the replacing ofthe semiconductor layers SL with the conductive material may includeforming a metal nitride layer or a metal layer to conformally cover theexposed portions of the semiconductor layers SL.

During the replacing of the semiconductor layers SL, other portions ofthe semiconductor layers SL that are overlapped by (e.g., veiled with)the third insulating layer IL3 may be protected. In some embodiments,the overlapped/veiled portions of the semiconductor layers SL mayconstitute the semiconductor patterns SP. The channel region CH, thefirst impurity region SD1, and the second impurity region SD2 may bedefined in each of the semiconductor patterns SP. The first and secondimpurity regions SD1 and SD2 may be remaining portions of the dopedregions DR, which are not replaced with the conductive material in thereplacing of the semiconductor layers SL. The channel region CH may belocated between the first and second impurity regions SD1 and SD2.

Referring to FIGS. 27 and 28A to 28C, a fourth insulating layer IL4 maybe formed on the substrate 100 in (e.g., to fill) empty spaces in thestack SS. The fourth insulating layer IL4 may be formed of or include aninsulating material having an etch selectivity with respect to the thirdinsulating layer IL3. The fourth insulating layer IL4 may be formed ofor include at least one of silicon oxide, silicon nitride, or siliconoxynitride. For example, the fourth insulating layer IL4 may include asilicon oxide layer.

The third insulating layer IL3 may be selectively removed to form thirdtrenches TR3. In some embodiments, the supporting layers SUP may not beremoved during the formation of the third trenches TR3. The formation ofthe third trenches TR3 may include forming a third mask pattern having athird opening exposing the third insulating layer IL3, selectivelyetching the third insulating layer IL3 using the third mask pattern asan etch mask, and removing the third mask pattern. The third maskpattern may be formed on (e.g., to cover) the supporting layers SUP.After the formation of the third trenches TR3, the stack SS includingthe first conductive lines CL1, the semiconductor patterns SP, and thefirst electrodes EL1 and the fourth insulating layer IL4 may remain onthe substrate 100.

Referring to FIGS. 29 and 30A to 30C, the gate insulating layers GI andthe second conductive lines CL2 may be formed in the third trenches TR3.In detail, the gate insulating layers GI may be formed to conformallycover the semiconductor patterns SP exposed through the third trenchesTR3. A conductive layer may be formed on the gate insulating layers GIto define a perimeter around (e.g., to surround a periphery of) thesemiconductor patterns SP and then may be patterned to form the secondconductive lines CL2. The second conductive lines CL2 may be formed tobe spaced apart from each other in the first direction D1. Theconductive layer may be formed of or include at least one of dopedsemiconductor materials, conductive metal nitrides, metals, ormetal-semiconductor compounds. Each of the second conductive lines CL2may be formed to define a perimeter around (e.g., to surround aperiphery of) the semiconductor patterns SP, which are verticallystacked, and to extend in the third direction D3.

Referring to FIGS. 31 and 32A to 32C, a fifth insulating layer IL5 maybe formed in (e.g., to fill) empty spaces in the third trenches TR3. Thefifth insulating layer IL5 may be formed on (e.g., to cover) a topsurface of the fourth insulating layer IL4. The fifth insulating layerIL5 may be formed of or include at least one of silicon oxide, siliconnitride, or silicon oxynitride. For example, the fifth insulating layerIL5 may include a silicon oxide layer.

A third patterning process may be performed to selectively expose thefirst electrodes EL1. For example, the third patterning process mayinclude forming a fourth mask pattern having fourth openings,selectively etching the fourth and fifth insulating layers IL4 and IL5using the fourth mask pattern as an etch mask, and removing the fourthmask pattern. The fourth openings may be formed to expose portions ofthe fifth insulating layer IL5 that overlap the first electrodes EL1.

Referring back to FIGS. 10 and 11A to 11C, the dielectric layer DL maybe formed on (e.g., to conformally cover) the exposed surfaces of thefirst electrodes EL1. The second electrode EL2 may be formed on thedielectric layer DL to define a perimeter around (e.g., to surround aperiphery of) the first electrodes EL1. Each of the first electrodesEL1, the dielectric layer DL, and the second electrode EL2 mayconstitute the capacitor DS. Moreover, as used herein, the words“surround a periphery of” are not limited to surrounding or coveringevery surface/side of an element. For example, a periphery of an elementmay include four sides/surfaces of the element, and does not necessarilyinclude five or six sides/surfaces. As an example, a periphery mayinclude a top surface, a bottom surface, and opposing side surfaces, anddoes not necessarily include end surfaces.

In a three-dimensional semiconductor memory device according to someembodiments of present inventive concepts, memory cell transistors andcapacitors may be three-dimensionally arranged on a substrate.Accordingly, it is possible to increase an integration density of amemory device.

The above-disclosed subject matter is to be considered illustrative, andnot restrictive, and the appended claims are intended to cover all suchmodifications, enhancements, and other embodiments, which fall withinthe true spirit and scope. Thus, to the maximum extent allowed by law,the scope is to be determined by the broadest permissible interpretationof the following claims and their equivalents, and shall not berestricted or limited by the foregoing detailed description.

What is claimed is:
 1. A semiconductor memory device comprising: asubstrate; a plurality of memory cell transistors vertically stacked onthe substrate; a first conductive line connected to a source region ofat least one of the plurality of memory cell transistors; a secondconductive line connected to a plurality of gate electrodes of theplurality of memory cell transistors; and a data storage elementconnected to a drain region of the at least one of the plurality ofmemory cell transistors, wherein the data storage element comprises afirst electrode that extends horizontally from the drain region in afirst direction parallel to a top surface of the substrate, wherein afirst one of the first conductive line or the second conductive lineextends horizontally in a second direction that intersects the firstdirection, wherein a second one of the first conductive line or thesecond conductive line extends vertically in a third direction that isperpendicular to the top surface of the substrate, wherein the firstelectrode extends longer in the first direction than in either of thesecond and third directions, wherein the first one of the firstconductive line or the second conductive line extends longer in thesecond direction than in either of the first and third directions, andwherein the second one of the first conductive line or the secondconductive line extends longer in the third direction than in either ofthe first and second directions.
 2. The semiconductor memory device ofclaim 1, wherein the at least one of the plurality of memory celltransistors comprises a semiconductor pattern comprising the sourceregion, the drain region, and a channel region that is between thesource region and the drain region, and wherein the semiconductorpattern extends from the first conductive line in the first direction.3. The semiconductor memory device of claim 2, wherein the semiconductorpattern and the first electrode comprise respective surfaces that arecoplanar, and wherein the semiconductor pattern and the first electrodecomprise respective extension axes that are parallel to the firstdirection and are coaxial.
 4. The semiconductor memory device of claim1, wherein the second conductive line defines a perimeter around aplurality of channel regions of the plurality of memory celltransistors.
 5. The semiconductor memory device of claim 1, wherein thedata storage element comprises a first capacitor that is adjacent thesecond conductive line, wherein the first capacitor comprises the firstelectrode and further comprises: a dielectric layer on the firstelectrode; and a second electrode on the dielectric layer, and whereinthe semiconductor memory device further comprises a second capacitorthat is adjacent the second conductive line and that overlaps the firstcapacitor in the third direction.
 6. The semiconductor memory device ofclaim 1, wherein the first electrode comprises a first end portion thatis adjacent and connected to the drain region, wherein the firstelectrode further comprises a second end portion that is opposite thefirst end portion, and wherein an axis that extends through the firstend portion and the second end portion is parallel to the firstdirection.
 7. The semiconductor memory device of claim 6, furthercomprising a first supporting layer that is connected to the second endportion of the first electrode and is configured to structurally supportthe first electrode.
 8. The semiconductor memory device of claim 7,further comprising a second supporting layer that is between the firstend portion and the second end portion of the first electrode and isconfigured to structurally support the first electrode.
 9. Thesemiconductor memory device of claim 1, further comprising a back-gateline that is adjacent a plurality of channel regions of the plurality ofmemory cell transistors and that extends in parallel with the secondconductive line.
 10. A semiconductor memory device comprising: asubstrate; a plurality of structures that are vertically spaced apartfrom each other in a stack on the substrate, wherein each of theplurality of structures respectively, comprises: a semiconductor patternthat comprises a first impurity region, a channel region, and a secondimpurity region; and a first electrode of a capacitor that is connectedto the second impurity region, and wherein each of the plurality ofstructures extends horizontally in a first direction that is parallel toa top surface of the substrate.
 11. The semiconductor memory device ofclaim 10, wherein the semiconductor pattern and the first electrodecomprise respective surfaces that are coplanar, and wherein thesemiconductor pattern and the first electrode comprise respectiveextension axes that are parallel to the first direction and are coaxial.12. The semiconductor memory device of claim 10, wherein the pluralityof structures overlap each other in a vertical second direction that isperpendicular to the top surface of the substrate.
 13. The semiconductormemory device of claim 10, further comprising: a first conductive lineconnected to the first impurity region of the semiconductor pattern; anda second conductive line that surrounds a periphery of the channelregion of the semiconductor pattern, wherein the first conductive lineextends horizontally in a second direction that crosses the firstdirection, wherein the channel region comprises one among a plurality ofchannel regions of the plurality of structures, and wherein the secondconductive line extends vertically in a third direction that isperpendicular to the top surface of the substrate, to surroundperipheries of the plurality of channel regions.
 14. The semiconductormemory device of claim 13, further comprising a back-gate line, whereinthe back-gate line extends parallel to the second conductive line in thethird direction, to surround the peripheries of the plurality of channelregions.
 15. The semiconductor memory device of claim 10, wherein thecapacitor further comprises: a dielectric layer that is on the firstelectrode; and a second electrode that is on the dielectric layer,wherein the first electrode comprises one among a plurality of firstelectrodes of the plurality of structures, wherein the capacitorcomprises one among a plurality of capacitors of the semiconductormemory device, and wherein the second electrode comprises a commonelectrode of the plurality of capacitors.
 16. The semiconductor memorydevice of claim 10, further comprising a supporting layer that isconnected to an end portion of the first electrode, wherein thesupporting layer is configured to structurally support the plurality ofstructures.
 17. A semiconductor memory device comprising: a substrate; avertical stack comprising a plurality of layers on the substrate; and afirst conductive line that is penetrated by the vertical stack and thatextends in a vertical direction perpendicular to a top surface of thesubstrate, wherein each of the plurality of layers of the vertical stackcomprises: a first extended portion that extends horizontally in a firstdirection parallel to the top surface of the substrate; and a secondextended portion that extends horizontally from the first extendedportion in a second direction parallel to the top surface of thesubstrate and crossing the first direction, wherein the first extendedportion comprises a second conductive line, wherein the second extendedportion comprises a semiconductor pattern and an electrode that isconnected to the semiconductor pattern, wherein the semiconductorpattern is between the second conductive line and the electrode, andwherein the first conductive line is on a top surface and a bottomsurface of the semiconductor pattern that are each parallel to the topsurface of the substrate.
 18. The semiconductor memory device of claim17, wherein the semiconductor pattern comprises a first impurity region,a second impurity region, and a channel region that is between the firstimpurity region and the second impurity region, wherein the secondconductive line is connected to the first impurity region, and whereinthe electrode is connected to the second impurity region.
 19. Thesemiconductor memory device of claim 17, wherein, in each of theplurality of layers in the vertical stack, the second extended portioncomprises one among a plurality of second extended portions, wherein theplurality of second extended portions are connected in common to thefirst extended portion, and wherein the plurality of second extendedportions are spaced apart from each other in the first direction. 20.The semiconductor memory device of claim 17, further comprising asupporting layer that is configured to structurally support theplurality of layers, wherein the electrode comprises a first electrodeof a capacitor, wherein the capacitor further comprises: a dielectriclayer on the first electrode; and a second electrode on the dielectriclayer, and wherein the first conductive line is on opposite sidesurfaces of the semiconductor pattern.